-- German Chancellor Angela Merkel was today placed by Forbes Magazine at the top of its annual list of the World’s 100 Most Powerful Women.
Merkel, elected in 2005, is the first female chancellor of Germany. Daughter of a pastor and a language teacher, she studied physics at the University of Leipzig and learned to speak fluent Russian.
In these images, we look back at other historic women leaders, from ancient times to modern day.

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Queen Hatshepsut (1503-1482 B.C.)
One of the most successful pharaohs in Egyptian history, Queen Hatshepsut brought long-standing peace and wealth to Egypt, mostly due to successful military campaigns waged early on in her rule. That prosperity enabled her to initiate unprecedented building projects, such as monuments at the Temple of Karnak, which furthered architecture and the arts in the ancient world.

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Cleopatra (69-30 B.C.)
Several female Egyptian leaders had the name Cleopatra, but the most famous was Cleopatra VII, ancient Egypt's last pharaoh. Before her tragic death -- likely by suicide to avoid capture and to maintain her own honor -- Cleopatra forged a liaison with Roman military and political leader Gaius Julius Caesar. After Caesar's assassination, she continued the alliance with Rome by entering into a relationship with Roman general Mark Antony, an influential Roman politician with whom she had twins.

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Empress Theodora (500-548)
Although born into the lowest class of Byzantine society, Theodora was a beautiful, famous actress who wound up marrying Emperor Justinian I. As Empress, she strengthened the Eastern Christian Church and was later made a saint in the Orthodox Church. She also was well ahead of her time in supporting women's rights issues, by doing things such as establishing punishment for rape, granting women rights in divorce cases and allowing women to own and inherit property.

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Queen Elizabeth I (1533-1603)
The last monarch of the Tudor dynasty and a daughter of Henry VIII, Elizabeth I was perhaps the polar opposite of her mother, Anne Boleyn. Elizabeth never married and instead threw herself into her work. She prevented France from using Scotland as a military stronghold and blocked the Spanish threat to England. The peace and prosperity of her rule led to one of the greatest periods in English literature. Known as the Elizabethan Age, it produced such playwrights as Chrisopher Marlowe and William Shakespeare.

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Catherine the Great (1729-1796)
As Empress of Russia, Catherine the Great extended the borders of the Russian Empire, adding some 200,000 miles to the Russian territory. Through successful military campaigns and negotiations, she made her country the dominant power in southeastern Europe. A believer in enlightened absolutism, she encouraged religious tolerance, freedom of speech, the arts and education.

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Queen Liliuokalani (1838-1917)
The last monarch of the Kingdom of Hawaii, Queen Liliuokalani fought to establish a constitution that would have granted voting rights to economically disenfranchised Native Hawaiians and Asians. A proponent of the traditional culture and her family's right to rule, Liliuokalani was viewed as a threat by some American and European leaders. She was arrested and jailed in 1895 and agreed to abdicate in return for the release of her jailed supporters. Hawaii was annexed to the United States in 1898 after the Spanish American War.

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Golda Meir (1898-1978)
Having served as Minister of Labor and Foreign Minister, Golda Meir became the fourth prime minister of the State of Israel in the politically turbulent 1969-1974 period. She was an early negotiator between Palestinian Jews and British Mandatory authorities. In 1948, she also was one of the 24 signatories of the Israeli declaration of independence. After a courageous battle against cancer, Meir died in Jerusalem at the age of 80 after a lifetime of having served her people and her state.

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Indira Gandhi (1917-1984)
For three consecutive terms from 1966-1977, Indira Gandhi was the Prime Minister of India. Her leadership coincided with a very difficult period that altered the power between the central authorities and the Indian states. After a victorious war against Pakistan, she returned to office and became involved in an escalating conflict with Punjab separatists. This led to her assassination, by her own bodyguards, in 1984. Indira Gandhi was India's first and only female prime minister.

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Eva Peron (1919-1952)
After a poor, abusive upbringing, Eva Duarte met and married Colonel Juan Peron, who later became President of Argentina. A strong individual in her own right, she tried to run for Vice President, but the establishment and her failing health prevented her from doing so. While dying from cancer at a young age, Eva Peron was given the honorary title, "Spiritual Leader of the Nation." Composer Andrew Lloyd Webber further immortalized her in his popular musical, "Evita."

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Margaret Thatcher (1925-)
The daughter of a grocery shop owner, Thatcher officially began her political career in the 1950's, when she ran in various elections, such as local Labor seats, and slowly rose up the ranks. From 1979 to 1990, she served as Prime Minister of the United Kingdom and is the only woman ever to have held that position. From 1975 to 1990, she was also the leader of the Conservative Party. Again, she is the only woman to have ever held this position. With U.S. president Ronald Reagan, she helped define conservative politics that guided the western world's leadership for over a decade.

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Violeta Chamorro (1929-)
From 1990 to 1997, Chamorro served as the 48th President of Nicaragua. To date, she is the only woman to have ever held that office. A member of the National Opposition Union, she was part of a coalition of 14 political parties that ran against the leftist Sandinistas. Although the alliance fell apart after her election to the presidency, Chamorro brought peace back to a country that had been at war for over a decade.

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Corazon Aquino (1933-)
The widow of assassinated senator Benigno Aquino, Jr., Corazon Aquino bravely entered politics on her own after her husband's death. She served as president of the Philippines from 1986-1992 and was the first woman to hold that position. In rising to that office, she also became Asia's first ever female president. Facing numerous military coups, she still maintained her democratic principles. In 1987, a new constitution was drafted, leading to a government based on popular and democratic mandates. In 1986, Aquino was named Time Magazine's "Woman of the Year."

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Wilma Pearl Mankiller (1945-)
The first female chief of the Cherokee Nation, Mankiller took on low-paying jobs with the Cherokee Nation to help her people. Entering leadership roles, she faced opposition from the male-dominated infrastructure. Desiring a more inclusive vision, she established community projects that brought men and women together. During her position as Chief, the Cherokee Nation's population increased from 55,000 to 156,000.

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Aung San Suu Kyi (1945-)
For the Burmese people, Aung San Suu Kyi represents the lasting hope that there will one day be an end to the country's controlling military junta. As a pro-democracy campaigner and leader of the opposition National League for Democracy party (NLD), she has spent more than a decade in some form of detention under the country's military regime. In 1991 she was awarded the Nobel Peace Prize for her efforts to bring democracy to Burma.

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Benazir Bhutto (1953-2007)
The first woman elected to lead a Muslim state, Benazir Bhutto served as Prime Minister of Pakistan from 1993 to 1996. A graduate of Radcliffe College at Harvard University, Bhutto was an eloquent and passionate speaker who was loyal to her family and her people. She decried terrorist acts, which forced her to take a stance against the Taliban and its supporters. Hoping to initiate political reforms in Pakistan, she attended a political rally for Pakistan People's Party on December 27, 2007. While waving to the attending crowds, Bhutto was shot and killed by an assassin who blew himself up afterward. At least 20 other people also died in the tragedy.

Hundreds of thousands of military positions remain closed to females. What's holding them back?

This week, four female members of the military filed a lawsuit challenging the Pentagon's ban on women serving in combat. The women say that because they cannot serve in battle, they are unable to acquire the necessary accolades that allow them to be promoted into as many as 238,000 positions across the Armed Forces.

Back in February, the Defense Department announced new policies that eased restrictions on jobs women could do in the military, opening up more than 14,000 positions to women and allowing them closer than ever to the front lines.

But embedded in that news was a long list of positions that were still closed to women, including infantry branch officers and members of special operation missions. That has caused some people to wonder: What's holding the government back from offering true equality to women in the armed forces?

The official reason for sustained gender roles is that "there are practical barriers," said DOD spokeswoman Eillen Lainez, "which if not approached in a deliberate manner, could adversely impact the health of our service members and degrade mission accomplishment."

History, too, may play a role, say researchers who cite conservative views that date back to the Revolutionary War. Traditional attitudes make many people both uncomfortable with the idea of women fighting and unable to handle the image of mothers coming home in body bags.

Republican candidate recently expressed this sentiment during an interview with NBC's "Today Show." The former senator from Pennsylvania was concerned that male soldiers would just want to protect fellow women soldiers during a fight, explaining, "when see a woman in harm's way…It's natural. It's very much in our culture to be protective."

There are also concerns that women will interfere with group bonding and cohesion – the same arguments that long interfered with the integration of African Americans and gay people into the military.

But on the ground, according to anecdotal reports, women at war are already doing many more combat-like activities than their job descriptions imply, making it hard for them to get the recognition they deserve or to advance to top-level positions. As women continue to push for more equality (as they have been for more than a century), it may be only a matter of time before they are officially allowed to do everything that male soldiers do – and finally get acknowledged for it.